Soon after Todd was found hanging from the bathroom door in his Singapore apartment on June 24, 2012, Singapore's medical examiner concluded he had killed himself.

But Todd's parents disagreed and hired a pathologist in the United States who -- based on Singapore's autopsy report and photographs of the body -- suggested there was evidence that his death was a homicide.

The latest ruling by the coroner sides with the medical examiner's assessment.

"The cause of the deceased's death was asphyxia due to hanging," the coroner's report said.

In it, Chay said Todd had "entertained suicidal ideations of overall increasing severity" in the months leading up to his death.

The United States Embassy in Singapore said the inquiry was "comprehensive, fair, and transparent."

"The coroner heard testimony from a wide range of witnesses in open court and received evidence in the form of written statements and records," it said in a statement Monday.

The decision is unlikely to appease Todd's family. CNN was unable to reach them for a reaction early Monday morning.

Singaporean lawyers hired by the Todd family have suggested Singapore's police work was sloppy and that an assumption of suicide led police to neglect other evidence.

During inquiry proceedings last month, the Todds' lawyers asserted a possible crime scene was altered: Todd's hanging body was cut down and laid on the floor and a nearby chair moved before a forensics team and photographer arrived. Police maintain this follows standard procedure.

The 31-year-old Todd had been working for a year and a half at the Singapore government's Institute of Microelectronics (IME) when he decided to quit his job and return home to the United States.

He was part of a team researching uses of Gallium Nitride (GaN), a semiconductor that can operate at extremely high temperatures.

Documents found on Todd's laptop after his death reportedly indicate IME may have had plans with Chinese telecom giant Huawei to co-develop an amplifier using GaN. Such a device could have both military as well as civilian uses.

Todd's parents believe their son may have been murdered over his knowledge of such a sensitive project. They say their son had warned them his life was in danger.

Both IME and Huawei deny that any joint GaN project ever went forward.

'Burden to those around me'

On the night of June 24, 2012, Todd's girlfriend Shirley Sarmiento, a nurse, discovered his body. She had gone to the apartment after he didn't answer calls or texts.

During the court proceedings, Sarmiento testified she didn't know the details of Todd's work but said Todd told her "how much he hated" it.

On one occasion he told her he was "working on something that could get him into trouble with the American government" and that "heavy hands" were coming after him, though he didn't elaborate.

But Todd had also confided in his girlfriend that he had been depressed since October 2011. But she said he "did not display any suicidal tendencies."

On his laptop, authorities found a two-page suicide note.

"I am so sorry it has come to this but I feel I am just a burden to those around me. I have tried to get jobs in the U.S. but I know I am not capable of fulfilling the duties required of me," he said in one.

What led to death?

In his report, the coroner says Todd did not possess confidential information from his work at IME and the GaN project did not materialize.

"At the time of his death, the major stressor in the deceased's mind was unlikely to be his workload," the coroner said.

Todd had already put in his 60-day notice to leave his job and his workload had decreased,

"Why then would the deceased commit suicide before he was due to return to the US?" Chay posed in the report.

He then hazards some guesses.

Todd was concerned he won't be able to get Defense Department clearance for a new job "because of his perceived involvement in violating US security, the possibility," and about his psychiatric condition, Chay wrote.

"These concerns in all likelihood caused him to feel that his deep sense of failure (which was magnified by his psychiatric anxiety) would follow him back to the US," the coroner concluded. "In the deceased's mind, all these factors eventually outweighed the happy prospects of reuniting with his family in the US and culminated in his ultimate decision to take his own life."